


The Chemistry of Love

by bornquiet



Category: Star Trek: The Original Series
Genre: Amok Time, First Kiss, M/M, Pon Farr, Wikipedia science, don't look at me, fake Vulcan biology
Language: English
Status: Completed
Published: 2016-08-30
Updated: 2016-08-30
Packaged: 2018-08-11 22:14:47
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,167
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7909603
Author URL: https://archiveofourown.org/users/bornquiet/pseuds/bornquiet
Summary: <blockquote class="userstuff">
              <p>Leonard asks Spock about Vulcan brain chemistry during pon farr. He learns more than he ever expected to.</p>
            </blockquote>





	The Chemistry of Love

**Author's Note:**

> This fic picks up exactly where the episode Amok Time leaves off, so I have included the dialogue from the very end of the episode, found [here](http://www.chakoteya.net/StarTrek/34.htm). It's probably better to watch the end of the episode though.

MCCOY: Spock, what happened down there? The girl? The wedding?  
SPOCK: Ah, yes, the girl. Most interesting. It must have been the combat. When I thought I had killed the captain, I found I had lost all interest in T'Pring. The madness was gone.  
(Intercom whistle)  
KIRK: Kirk here.

[Bridge]

UHURA: Captain Kirk. Message from Starfleet Command, top priority.

[Sickbay]

KIRK: Relay it, Lieutenant.

[Bridge]

UHURA: Response to T'Pau's request for diversion of Enterprise to planet Vulcan

[Sickbay]

UHURA [OC]: Hereby approved. Any reasonable delay granted. Komack, Admiral, Starfleet Command.  
KIRK: Well, a little late, but I'm glad they're seeing it our way. How about that T'Pau? They couldn't turn her down. Mister Chekov, lay in a course for Altair Six. Leave orbit when ready. Kirk out.  
MCCOY: There's just one thing, Mister Spock. You can't tell me that when you first saw Jim alive that you weren't on the verge of giving us an emotional scene that would have brought the house down. .  
SPOCK: Merely my quite logical relief that Starfleet had not lost a highly proficient captain.  
KIRK: Yes, Mister Spock. I understand.  
SPOCK: Thank you, Captain.  
MCCOY: Of course, Mister Spock, your reaction was quite logical.  
SPOCK: Thank you, Doctor.  
MCCOY: In a pig's eye!  
KIRK: Come on, Spock. Let's go mind the store.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Leonard basks in the warmth of winning another argument with Spock for a moment before he comes back to himself. He sticks his head out of the door and calls down the corridor, “Hold on there Mr. Spock! I need to check you over.”

The captain and his first officer turn around simultaneously, Jim with a knowing smirk and Spock with an eyebrow raised. “I can assure you, Doctor, I am perfectly fine. There is no need to wave your rattles over me.”

A couple of crewman pause in the corridor with grins on their faces. Leonard feels his good mood dissipating as Jim’s smirk turns into a chuckle. He scowls. Well, if the crew is expecting a show, then by God they are going to get one! “I think I’ll be the judge of that Spock! You just went through some extreme changes in body chemistry, and unless you want me to stand here in the corridor and list all of the ways that could wreak more havoc on your body than a bull in a china shop, you better get your Vulcan superiority complex back in here!”

“Perhaps you should listen to Bones, Spock.” Jim’s smile had turned into a small frown, and he looked worried. “After all, he is right. I want to make sure you are at your best after what just happened. Maybe just a quick checkup instead of a full physical.”

“. . . Yes captain.” Jim heads for the turbolift as Spock begins to walk back towards Sickbay, leveling a look at the crewmen who are still watching the show. The grins drop simultaneously from their faces, and they turn around in sync and head away from Spock, heads down. Leonard waits for Spock to pass him and sit on a biobed before he goes into his office to grab his tricorder. The satisfaction of getting Spock back in Sickbay is warring with worry over his health. Leonard has learned that Vulcans have been doing this particular song and dance for centuries, but Spock is only half Vulcan, dammit! Who knows what that hyper-fast Vulcan equivalent to going into heat did to his systems.

Leonard heads out to the biobed where Spock is sitting, perfectly straight and obviously disdainful. Leonard nearly bristles before he remembers that he is worried. He needs to be professional long enough to ensure Spock is okay before he can win another argument with the green-blooded bastard. “That was quite the ceremony down on Vulcan,” Leonard remarks casually as he begins to scan Spock with the tricorder, keeping an eye on the biobed’s readouts. They look alright but he wants to make absolutely certain that Spock is okay.

“I have noticed that it takes you 5.243 times longer to perform an examination when you participate in the human habit of ‘small talk’. Please refrain from doing so, I must get back to the bridge.”

Leonard stops scanning Spock and stares, flabbergasted. He nearly has a coronary on the spot. Of all the rude, condescending bullshit. . .

Instead of exploding, as he is sure Spock was hoping and going for, he closes his eyes and takes a deep breath. Then he begins to upload the tricorder’s readings to a padd for analysis. He reminds himself again that he can’t fall for Spock’s manipulations. He needs to make sure he is alright before the arguments can start. Besides, it’s no fun when Spock is the one getting a rise out of him.

“I imagine that if I scanned you during that battle with Jim, your readings would be very different than they are now. When I gave you a physical earlier, I was mostly concerned with the massive amounts of adrenaline flooding your body, but I’ve had time to look and it wasn’t the only change that was occurring. Your testosterone and vasopressin levels were through the roof, and your oxytocin levels were up compared to your normal levels as well, even though testosterone blocks oxytocin. What causes all of this to happen?”

Spock gives a nearly audible sigh, which causes Leonard to smile smugly, before he answers, “I imagine you will continue with this line of questioning whether I respond or not. I will answer your questions, if only to prevent you jumping to extreme and inaccurate conclusions.” Leonard’s smile widens, but he doesn’t say anything. He is pretending to continue his examination even though he is done and Spock is fine. His testosterone levels are still a little high but nothing serious is going on. Keeping Spock here is more out of professional (and perhaps personal, although he will never admit it) curiosity. He wants to know what happened to Spock’s body down there.

“The answer to your question is rooted partially in the history of Vulcan. You know of Surak, correct?” Leonard nods. The very first pointy-eared know-it-all, he almost says. The standard History of the Federation course went over the Vulcan extensively in the academy. “When Surak’s teachings of complete logic became widespread, Vulcans began to regulate their more base urges through meditation. This caused lower levels of testosterone and estrogen, as those neurochemicals control the sex drive.”

Leonard is unsuccessful in his attempt to prevent himself from rolling his eyes. “I’m a doctor, not a starship captain. I know what testosterone and estrogen do.”

Spock levels a look at him. “Indeed. If I may continue my explanation?” Leonard nearly rolls his eyes again, but nods instead. It wouldn’t do much good to rile Spock up before he got to the interesting parts.

“As you noted earlier, Doctor, testosterone suppresses oxytocin. Therefore, the decrease of testosterone in Vulcan males led to an increase in oxytocin in the same. Vulcans are far more private than any other species, but they still feel the need for companionship. That need increased after Surak due to this increase in oxytocin. This is why Vulcans bond, and do so for life.”

“The Vulcan brain adapted quite quickly to this change, but there was one thing that did not change. Dopamine levels stayed the same in our brains. Dopamine levels are much higher in Vulcans than they are in humans, as dopamine is important for cognitive flexibility and our touch telepathy. Dopamine is the reason why Vulcans are far more focused and motivated than humans, and is why we are more attuned to logic.”

Leonard snorts at that. He has given up even the pretense of examining Spock at this point. He is far more interested in what Spock is telling him. “Doesn’t dopamine also control arousal and sexual gratification?” Leonard wiggles his eyebrows. “Have you ever had an inappropriate reaction to someone because of your ‘much higher dopamine levels’?”

He gets the feeling that if it wasn’t a sign of emotion, Spock would be rolling his eyes right now. He sits up as he replies mildly, “Indeed not, Doctor. Vulcans are perfectly capable of controlling their arousal. However. . .” Leonard notices that Spock’s posture gets even more perfect as his hands fold in his lap. He is no longer looking at Leonard as he continues.

“While Vulcan males can control their arousal, the levels of dopamine in their system do require a release. If they do not get release regularly, and often even if they do, their bodies will become stressed, as you have already observed. Adrenaline levels increase in an attempt to give the male enough energy to get the release he needs. Eventually it gets to the point where the body demands release. That is when pon farr begins.”

Leonard outright chuckles at that. “So even you high and mighty ever-so-logical Vulcans have biological imperatives that you can’t control. Certainly, human males get cranky when they have not had an orgasm for some time, but that’s taking the term ‘blue balls’ to a whole new level! What about Vulcan females? They don’t go through pon farr, do they?”

“No, they do not. Vulcan females have always had less estrogen than Vulcan males had testosterone. The violence of Vulcan society pre-Surak was caused by Vulcan males, not Vulcan females. Therefore, it was the Vulcan males that went through the most changes during the time Surak was alive. Vulcan females act much the same as they have for centuries, albeit a bit more logically.”

Leonard frowns. “I suppose that makes sense. They don’t need the same kind of release because they didn’t go through as many changes.” He ignores Spock’s dry, “That is what I just said, Doctor.”

“I still don’t understand why your attraction to and desire for T’Pring completely disappeared when you thought you had killed the captain though. Attraction doesn’t just disappear like that, even for green-blooded logic machines like Vulcans!”

“Pon farr is not about attraction, Doctor. It is similar to attraction only in that it is a biological imperative meant to propagate the species. Attraction to a bondmate is possible outside of pon farr. My father is such an example. However, it is unnecessary and infrequent. Vulcans, as I believe you are well aware, have lower levels of oxytocin than humans. Those levels are slow to raise in response to the companionship of another, if they do at all. Were you to spend some time on Vulcan, you would notice that bonded pairs act more like humans who are close friends than humans who are in love.” Leonard snorts as Spock gets up to leave. Of course.

“Of course it’s like that. A Vulcan wouldn’t know what to do with love if it hit them in the face with a heart-shaped baseball bat.”

Spock, impossibly, stiffens even more. He is more reminiscent of a board than a Vulcan at this point. It’s pretty clear that he is beyond done with this conversation, but Leonard can’t give it up.

“Love is an abstract concept, Doctor. It cannot hit anyone in the face, especially not with such an illogically shaped device.” Leonard begins to sputter, but Spock continues coolly. “Furthermore, my research shows that Vulcans can have a higher level of oxytocin outside of pon farr, as I have already mentioned. As I have also already mentioned, my father is an example of one who shows physical and romantic attraction to his bondmate outside of pon farr. It is rare, not impossible. I can not be certain because of slight differences in my own physiology, but I myself have exhibited some signs-“

Spock stops abruptly, his eyes widening. Leonard’s head is spinning at the implications. Is Spock saying what he thinks he’s saying? But who. . . oh. Again, of course. And he can’t even tease the disgustingly straightforward Spock, who could not possibly be comfortable talking about this. Leonard certainly doesn’t want to. But his doctor instincts are screaming at him. Leonard knows Spock has to talk about it at some point. It’s so important for his human half.

Spock has turned toward the door. “I must do more research on the subject. Please excuse me Doctor.”

“It’s Jim, isn’t it?” Leonard sighs in defeat as Spock stops dead. “After all, that near emotional display when you saw him alive was quite the sign.” He takes a hesitant step towards Spock. “It’s okay. Jim is an extraordinary guy. I won’t tell anyone, not even to tease you. Doctor patient confidentiality and all. You don’t have to be asham-“

“It is not the captain, Doctor.” Leonard watches in shock as Spock lowers his head. “I appreciate the sentiments you just expressed, even if they are misguided.” Leonard can practically feel the pain rolling off the Vulcan. Without thinking about it, he puts his hand on Spock’s elbow and turns him around. The fact that Spock does not resist worries him, but even more concerning is the look on the Vulcan’s face. He looks so defeated. Leonard immediately starts to bristle.

“What is it Spock? Did someone reject you? Who could possibly do such a thing? Don’t listen to them Spock,” he says fiercely. “Tell me who it is. How dare they!”

Spock looks, for lack of a better word, bemused. The effects of pon farr must still be in his system for him to be showing so much emotion. “Doctor, the person you would have to ‘have words with’ is yourself.” Immediately Spock goes green and turns, probably to beat a hasty escape. Leonard can tell he didn’t mean to say that. He probably would have escaped, but Leonard’s hand on his arm becomes an iron grip as the doctor processes what Spock just told him.

Spock. . . loves him? HIM? That can’t be right. He looks at the Vulcan, but Spock is studying the door with enough intensity to burn a hole in it. The fact that the confrontational bastard can’t look him in the eyes tells him everything he needs to know. Spock loves him.

“Why didn’t you tell me, Spock?” he demands. He has to know.

That causes Spock to look at him. “Doctor, you are constantly antagonizing me,” he says evenly. “You have never shown any indicator of friendship towards me that you have shown Captain Kirk or Lieutenant Commander Scott. I admit I am mostly unfamiliar with human relationships, but I believe friendship is a necessary precursor to human romantic relationships.”

Leonard blows up. “You’re dumber than a sack of rocks sometimes Spock! Of course you are my friend! But I was TRYING to get a rise out of that thick Vulcan hide! I needed to know that you could have emotions! I needed to know that you could have emotions because of me! That I could get to you! How else was I going to get you to love me?”

He hauls the wide-eyed Vulcan towards him and kisses him, hard. He pours all his concern, his frustration, his love, into that kiss. His eyes close in relief, only to open in horror at the realization of what he is doing. Spock never said this was okay! He pulls back, releasing Spock and stepping away.

He pants heavily as Spock stares at him, eyes dark and wide. Leonard’s emotions have been spiraling upwards, made worse by his attempts to hold back in order to finally learn more about Vulcans. He supposes that kiss was inevitable, but that does not make it any less excusable. Even if Spock says that he. . . he loves him, that doesn’t mean that Leonard is allowed to molest him, practically in public. Anyone could have walked in. He eyes Spock warily. Spock is still frozen. If the situation were more lighthearted, Leonard might be joking about a reboot right now. But it’s not, and he needs to apologize instead. Leonard sighs. “I’m sorry Spock, I shouldn’t have done that.” He turns around and begins clearing the station he had just examined Spock at. “You’re fine, you can go now.”

Leonard turns back around, tricorder in hand, only to bump into Spock’s chest. His surprised exclamation is cut short by cool lips pressed firmly against his. Leonard drops the tricorder, but Spock somehow manages to catch it and set it back on the table without breaking the kiss. Probably because of the telepathy, Leonard thinks hazily as Spock opens his mouth and tries to deepen the kiss. Despite instigating it, it is clear that he has very little experience.

One of Spock’s hands catches his and he rubs his first two fingers very purposefully against Leonard’s fingers. His other hand cradles Leonard’s head gently. Leonard’s shock is replaced with amusement as Spock clumsily runs his tongue along Leonard’s lips. Leonard’s free hand runs gently along Spock’s jaw, adjusting the angle and deepening the kiss properly. His eyes close as he loses himself in the feel of Spock pressed against him.

Spock eases away slowly, his hand still cradling Leonard’s head, fingers ghosting through his hair. “Leonard,” he whispers. Leonard’s eyes fly open at the sound of his first name. “I could only hypothesize that you did not care for me. I am sorry, ashayam, if I led you to believe that you never affected me. The opposite is true. I want to be with you.”

Leonard’s head is spinning. He pulls gently away from Spock’s embrace and sits on the biobed, muttering, “Give- give me a minute.” Now that he’s starting to process everything that’s happened, everything that’s been said, he feels like he’s been hit with a sledgehammer. He stares at the floor, his hands flexing on the edge of the bed. His first instinct is to ask the hobgoblin why the hell he would care for him when he could have anybody else. His second, more overwhelming one is to grin. Spock never lies. He prevaricates, he doesn’t provide the full picture, it’s frustrating as hell, but he never lies. And he said he cares for Leonard. He wants to be with Leonard.

The grin widens as he looks up at the Vulcan. He can’t help it. He has forced down his hopes time and time again, and now they are being realized. “So, Spock,” he says casually as he stands up and heads for the door. “How about skippin’ the bridge and joining me in my quarters for dinner? You could teach me how to make that plomeek soup.”

“Certainly, Doctor. Although it is a complicated recipe, I am not certain that you will be able to make it.” They walk out the door together as Leonard scoffs, although there is no real temper behind the sound. He is still smiling.

“I think if you can make it, I can manage. After all, I am the one with the talented hands in this relationship!” Leonard’s smile softens as Spock opens his mouth to reply. In this relationship. He sure could get used to that!

**Author's Note:**

> Disclaimer: I don't even really like biology. Chemistry is way better.


End file.
